Apparatus for the combustion of gas mixtures and vapor mixtures



April 28, 1970 M. LEMPP ET AL 3,508,851

APPARATUS FOR THE COMBUSTION OF GAS MIXTURES AND VAPOR MIXTURES Filed May 17, 1968 INVENTORS MATTHIAS LEMPP FRIEDRICH LORENZ ATT'YS United States Patent 015cc 3,508,851 APPARATUS FOR THE COMBUSTION OF GAS MIXTURES AND VAPOR MIXTURES Matthias Lempp, Mannheim, and Friedrich Lorenz, Ludwigshafen (Rhine), Germany, assignors to Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), Germany Filed May 17, 1968, Ser. No. 729,972 Claims priority, application Germany, May 18, 1967, 1,642,930 Int. Cl. F231 7/00 US. Cl. 431116 Claims ABSTRACT OF THE DISCLOSURE A burner for the partial oxidation of gas mixtures and vapor mixtures which is divided by a nozzle-shaped constriction into a pre-chamber and a combustion and gasification chamber, the burner wall having openings in the region of the constriction through which a branch stream of the unburned mixture can be supplied and/or withdrawn by means of a blower to stabilize the front of the flame.

This invention relates generally to methods for gasifying and burning gases or vapors and appropriate apparatus for the purpose. It relates in particular to a combustion chamber for the partial oxidation of gas mixtures and vapor mixtures in which the course of the combustion can be controlled and the flame front is stable.

In known equipment for the combustion of gas mixtures and vapor mixtures these are usually supplied through nozzles to the combustion chamber. In the case of burners which serve not for heat production but for carrying out chemical reactions, a large number of such nozzles is usually provided in one plane at the front end of the combustion chamber. Owing to the fact that the nozzles are necessarily arranged at a distance from each other it is impossible for a uniform flame front to form. This nonuniformity is intensified by the nonuniform feed to the individual nozzles. Moreover, backflow and the formation of eddies often occur behind the nozzles in the combustion chamber owing to changes in cross-section and resultant changes in pressure, and these similarly prevent quiet and trouble-free combustion. As a result of all these disturbances, a nonuniform field of temperature and velocity is set up in the combustion chamber in a plane perpendicular to the direction of flow.

The course of chemical reactions in such combustion chambers, as for example the partial oxidation in the production of acetylene, is similarly impaired by the nonuniform and consequently uncontrollable course of the combustion so that the optimal yield of cracked gas cannot be achieved. Furthermore the composition of the gas depends essentially on the course of the combustion. The fact that undesirable mixing of the constituents of the cracked gas present in the various planes of the burner takes place when the combustion process is subject to changes and affected by backflow, also makes it necessary to stabilize the flame.

Various methods and means for stabilizing a flame front have been described in the literature; these are mainly based on imparting to the flow of the fuel or gasifying agent a more or less marked twist, i.e. rotational flow. The known measures are unsuitable for carrying out partial oxidations of gas mixtures and vapor mixtures because secondary currents are invariably set up owing to the pressure gradient in the rotational field. The consequence of this is a nonuniform temperature field perpendicular to the burner axis.

3,508,851 Patented Apr. 28, 1970 Carbon black is formed as a byproduct in the partial oxidation of gas mixtures and vapor mixtures. In combustion chambers of the abovementioned known type the carbon black is deposited in the zones which are not affected by the flow (known as dead zones) and soon forms a hard crust which can only be removed with difficulty. Since the carbon black deposits progressively worsen the flow conditions, the combustion chamber becomes clogged up slowly at first and then more and more quickly so that the oxidation furnace has to be shut down.

The invention accordingly has for its object to provide a combustion apparatus for gas mixtures and vapor mixtures which, while avoiding the abovementioned defects, ensures uniform and undisturbed combustion and stability of the flame front.

This obpect is achieved with an apparatus which comprises a pre-chamber which receives the mixture and a constriction downstream of the same to which a combustion chamber of larger cross-section is attached via a frustoconical transition member containing ignition means and designed with a substantially constant increase in cross-section. According to the invention there are provided in such an apparatus, in a zone of the constriction and the frustoconical transition member lying axially upstream of the ignition means, a number of rows of openings in the chamber wall arranged peripherally which serve to supply and/or withdraw a branch stream of unburnt mixture (taken from other parts of the apparatus) through an annular chamber comprising one or more compartments connected with a blower. This arrangement not only ensures controllable positive flow in the region of the flame front, but also makes it possible to prevent, by suction or injection, separation of the boundary layer of the flowing mixture in the combustion chamber.

According to another feature of the invention, the closed annular chamber surrounding the openings in the chamber wall consists of two parts, one part of the annular chamber being in connection with the suction side of the blower and the other part with the pressure side so that part of the unburnt mixture in the zone of the transition member which widens out into the combustion chamber is removed by suction and supplied through the other compartment of the annular chamber to the constriction.

Further details of the invention are given in the following description which is given with reference to the drawings.

FIGURES 1 and 2 are diagrammatic elevations of two different designs of apparatus having the features of the invention. The apparatus preferably consists of cylindrical tube sections and conical casings. In both embodiments, the gas mixture or vapor mixture first passes into a pre-chamber 1 which at the downstream end tapers into a short conical section and mergesinto a coaxial nozzle-shaped constriction 2. The constriction 2 opens into a uniformly widening chamber formed by a frustoconical transition member 3 in which ignition means 4 are provided. Connected to the transition member 3 is a combustion chamber 5 in which the stable flame front is formed; this combustion chamber is preferably cylindrical, but its cross-section may increase slightly in the direction of flow of the combustion gas.

In the embodiment shown in FIGURE 1 a number of rows of interrupted slot-shaped openings 3a are provided downstream of the constriction 2 on peripheral lines in the casing of the transition member 3 leading to the combustion chamber 5. The rows are at different axial distances from the nozzle-shaped constriction 2. A partial stream of the mixture which in this axial zone has not yet been ignited is sucked out through the openings 3a and reintroduced in the main stream through openings 2a arranged in the zone of the constriction 2 and, like the openings 3a, evenly distributed on peripheral lines. Consequently a positive flow which can be controlled from outside is set up in the burner between the openings 2a and 3a. A two-compartment annular chamber 6 surrounds the constriction 2 and the conical transition member 3, the compartments 6a and 6b being connected with the suction side and pressure side of a blower 7. With the positions of the compartments 6a and 6b of the closed annular chamber, the slot-shaped suction openings 3a and the similar supply openings 2a shown in FIG- URE 1, the pressure drop set up in the interior of the apparatus in the vicinity of the constriction 2 is utilized, i.e. this pressure drop and the blower supplement each other in their action to produce the positive flow.

In the embodiment of appartus shown in FIGURE 2, a partial stream of the mixture branched off from the prechamber 1 is introduced into the zone of the diverging transition member 3 substantially parallel to the wall in order to exert a direct influence on the flow boundary layer. For this purpose the transition member which widens out into the combustion chamber 5 is composed of a member of short frustoconical members 31), 3c which are connected to each other in spaced coaxial relationship by radial webs. Provided there is adequate overlapping of the surfaces of the members 3b, 3c in the axial direction, there are formed annular slit-shaped openings 8 extending in the axial direction which cause a primary positive flow along the chamber wall when the mixture is introduced axially or slightly tangentially. In this case, a closed undivided annular chamber 6 is placed around the transition member 3 in the axial zone of these annular slit-shaped openings 8 and is connected to the pressure side of the blower 7.

The apparatus according to this invention, from the pre-chamber 1 through the nozzle-shaped constriction 2 to the combustion chamber 5, may be designed with other cross-sections, for example polygonal, rectangular or circular with a central core For each of these cross-sections the burner should be so designed that a smooth flow free from eddies and backfiow can develop. This, together with the positive withdrawal and return of a partial stream of the mixture, not only ensures undisturbed combustion with a quiet flame front, but also prevents deposititon of carbon black on the walls of the burner.

What we claim is:

1. Apparatus for combustion of combustible gas mixtures or vapor mixtures which comprises a pre-chamber for receiving the mixture, a nozzle-shaped constriction tubular member joined with the downstream end of said pre-chamber, a hollow transition member joined with the downstream end of said constriction member and having a passage therethrough of substantially uniformly increasing transverse cross-section, ignition means in said last-mentioned passage, a combustion and gasification chamber joined with the downtream end of said trans'tion member, said transition member having a plurality of slot-shaped passages therethrough in the region of sad constriction member, said slot-shaped passages being arranged in a plurality of circumferential rows upstream of said ignition means, an annular chamber about said region, and blower means connected to said annular chamber for partial withdrawal from and/or supply to the apparatus of unburned gas or vapor mixture via said passages.

2. Apparatus as claimed in claim 1 wherein said annular chamber is subdivided into two compartments, one compartment being connected with the suction side of said blower means and with the slot-shaped passages in the downstream portion of said transition member, and the other compartment being connected with the pressure side of said blower means and with a slot-shaped passage in the region of said constriction member, whereby a partial stream of unburned mixture is withdrawn from the downstream portion of said transition member and reintroduced upon passage through said blower means into said apparatus in the region of said constriction member.

3. Apparatus as claimed in claim 1 wherein the upstream portion of said transition member is composed of a plurality of concentric, overlapping, hollow frustoconical members with an annular space between the respective overlapping portion thereof to provide said slotshaped passages.

4. Apparatus as claimed in claim 3 wherein said annular chamber is a single compartment chamber surrounding said concentric frusto-conical members, and means connecting said annular chamber to the pressure side of said blower means.

5. Apparatus as claimed in claim 1 wherein said transition member is a hollow frusto-conical member having said slot-shaped passages in the upstream portion thereof.

References Cited UNITED STATES PATENTS 2,690,795 10/1954 Webb 431-188 EDWARD G. FAVORS, Primary Examiner 

